Effects Of Seed Size And Seedling Raising Methods On Seedling Growth Of Xanthoceras Sorbifolia Bunge

Xanthoceras sorbifolia Bunge is a unique functional oil tree species and main landscaping tree species in China,which has a wide range of application value and large-scale cultivation potential.However,Xanthoceras sorbifolia Bunge seedlings have developed main roots,scarce lateral roots,which rot easily after being damaged.The transplanting survival rate is low,and the long slow seedling stage and poor initial growth restrict its large-scale cultivation.In view of these problems,this study adopted the method of comparative test to analyze the response of the aboveground part and root growth process of Xanthoceras sorbifolia seedlings to seed size and seedling mode.To study the growth rhythm of Xanthoceras sorbifolia seedlings,and to explore the root configuration characteristics and development law of Xanthoceras sorbifolia,so as to provide reference for improving the seedling technology of Xanthoceras sorbifolia,cultivating Xanthoceras sorbifolia seedlings with developed roots and strong growth,and improving the survival rate of transplanting.The main findings are as follows:(1)The annual growth rhythm of annual seedling height,ground diameter,aboveground biomass and root biomass of Xanthoceras sorbifolia Bunge showed a ’ S ’ shape of ’ slow-fast-slow ’,which could be divided into three stages:early growth stage,rapid growth stage and late growth stage.There were significant differences in the duration of different stages of each index.Among them,the initial growth period of seedling height was 68 days(late March to mid-May),the rapid growth period was 108 days(late May to early September)and the late growth period was 72 days(early September to mid-November).The initial growth period of ground diameter was 99 days(late March to mid-June),the rapid growth period was 130 days(late June to late October),and the late growth period was 19 days(late October to mid-November).The initial growth period of aboveground biomass was 60 days(late March to mid-May),the rapid growth period was 91 days(mid-May to early August)and the late growth period was 97 days(mid-August to mid-November).The initial growth period of root biomass was 122 days(late March to mid-July),the rapid growth period was 87 days(mid-July to early October),and the late growth period was39 days(early October to mid-November).(2)The size of Xanthoceras sorbifolia seeds had a significant effect on seedling growth.The larger the size was,the better the seedling growth was.The seed size of 1.3cm should be used as an excellent seed identification index for cultivating Xanthoceras sorbifolia seeding.The size <1.3cm was small seed,and the size ≥1.3cm was large seed.The seedling height,ground diameter,aboveground and root biomass,root morphology and other indicators of large seed were better than those of small seed.(3)Compared with container seedlings,field seedlings’ seedling height were higher,the ground diameter were thicker,the root system were more developed,the absorbing roots were richer,and the biomass were larger.In other words,field seedlings were stronger and the root system was more developed than container seedlings.However,container seedlings had more root distribution on soil surface,which was more conducive to survival after transplanting.(4)The germination rate of Xanthoceras sorbifolia Bunge seeds soaked in warm water for 24 h was low in container seedling and field seedling.The germination rate of field seedling was 19.12%,and the germination rate of container seedling was 27.43%.The low germination rate and the difference between the two need further experimental analysis.